The phenomena of meteorology, also, were explained largely by the four elements. The upper air was believed to be akin to the fire above it, and was therefore calm and cloudless; while the lower air was supposed to be cloudy and disturbed by storms because of its proximity to water, the next element below it in the series.[83] Further, the belief in the possibility of the transmutation of elements was of use here. Air, for example, might be transmuted into water, or water into air.[84] As Isidore puts it: “[air] being contracted, makes clouds; being thickened, rain; when the clouds freeze, snow; when thick clouds freeze in a more disordered way, hail; being spread abroad, it causes fine weather, for it is well-known that thick air is a cloud, and a rarified and spread-out cloud is air.”[85] [83] _Etym._, 13, 7, 1. [84] _Etym._, 13, 3. [85] _Etym._, 13, 7. Almost side by side with this explanation of rain is another which says that rains “arise from an exhalation from land and sea, which being carried aloft falls in drops on the lands, being acted upon by the sun’s heat, or condensed by strong winds,” 13, 10, 2. Lightning is explained as caused by the collision of clouds (13, 9, 1); thunder, by their bursting (13, 8); the rainbow, by the sun shining into a hollow cloud (13, 10, 1). [Illustration: FIG. 2] The most remote fields are invaded by the four elements. It is by reference to them that the seasons are explained. Here use is made rather of their properties than of the elements themselves. “The spring is composed of moisture and heat; the summer, of fire and dryness; the autumn, of dryness and cold; the winter, of cold and moisture.”[86] From this the transition is easy to another far-fetched application of the theory. The four quarters of the universe, East, West, North, and South, are connected with the four seasons, and thus with the four elements. This conception seemed to Isidore so important that he introduced a figure to illustrate it. (_Fig. II._) [86] _D. N. R._, 7, 4. _Cf. Etym._, 5, 35, 1. [Illustration: FIG. 3] The old notion that man is a microcosm or parallel of the universe on a small scale, was familiar to Isidore. As has been shown, he believed that man was composed of the same four elements as the universe, and that they were distributed in him in much the same way as in it. It was going only a step further for him to declare that “all things are contained in man, and in him exists the nature of all things”;[87] after which it was easy “to place man in communion with the fabric of the universe”[88] by means of a figure. (_Fig. III._) [87] _Sent._, 1, 11, 1.